PE-22-RC-Retaining-Walls

# PE-22-RC-Retaining-Walls - 22 - Reinforced Concrete...

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22 - Reinforced Concrete Retaining Walls 01: Design a reinforced concrete wall for a sloped backfill. 02: Design a reinforced concrete bridge abutment wall. 539

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**RC Retaining Walls–01: Design a RC wall for a sloped backfill. (Revision: Oct-08) 1' 2' 15' 16'-6" 1'-6" 18.33' 1.83' P v P h 3 1 1 2 3 4 5 6 6.11' 3' 1'-6" 5'-6" 10' Design a reinforced concrete wall with a backfill γ = 125 pcf, an allowable soil bearing capacity of q all = 3 ksf, and a friction at the base of φ = 30º. Design the wall and check for it’s stability under working loads. ( Note: All loads, shears and moments are per linear ft. of retaining wall) . 560
Solution: () 22 2 Step 1: Find the lateral pressures and forces. The active lateral earth pressure is, 30 tan 45 tan 45 tan 30 0.33 The presure at the base (invert) of the wall footing is, a a ba K K pH K φ γ ° ⎛⎞⎛ = ⎜⎟⎜ ⎝⎠⎝ = ( ) ( ) 0.120 18.33 0.33 0.733 The forces on the wall (per unit length) are, ½(12)(18.33)² 2.0 ½(39)(18.33)² 6.6 Step 2: Stability analysis for sliding and overturning. v h kcf ft ksf Pk i p s i p s == Moment About A Area Area Force (kip) Arm (ft) Moment (kip-ft) 1 ½ x 5.5x 1.83 = 5.03 x 0.125 = 0.63 1.83 1.2 2 5.5 x 15.0 = 82.5 x 0.125 = 10.31 2.75 28.4 3 1.0 x 15.0 = 15.0 x 0.150 = 2.25 6.00 13.5 4 ½ x 0.5 x 15.0 = 3.75 x 0.150 = 0.56 6.67 3.7 5 10.0 x 1.5 = 15.0 x 0.150 = 2.25 5.00 11.3 6 3.0 x 2.0 = 6.0 x 0.125 = 0.75 8.50 6.4 P v 2.00 P h Σ H = 6.60 6.11 40.4 Σ V=18.75 Σ M=104.9 Location of Resultant From point A, 104.9 = 5.6 ft 18.75 then e = 5.6 – 10 = 0.6 ft o.k. < B 2 6 561

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Soil Pressure at Toe of Base q max = 18.75 (1 + 6 x 0.6 ) = 1.875 (1 + 0.36) = 2.55 ksf OK < 3 ksf 10 10 Check F against Sliding Shear available along base = 18.75 kips x 0.58 = 10.9 kips Passive force at toe Use S = 2/3 (30º) = 20º , P p = ( cos δ ) = 5.8 kips ½ γ P p = 5.8 (0.125) (3.5) ² = 4.7 kips 2 (0.940) Min. F = 10.9 = 1.7 kips , Max F = 10.9 + 4.7 = 15.6 = 2.4 kips OK without Key 6.6 6.6 6.6 Step 2 : Design parameters.
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## This note was uploaded on 09/07/2011 for the course CEG 4012 taught by Professor Staff during the Spring '10 term at FIU.

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PE-22-RC-Retaining-Walls - 22 - Reinforced Concrete...

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